This is a work log of my fourth ghettoblaster project. Here's the two first models I've built (2007) to give you the idea of my work:

For the year 2010 my goal is to make lighter yet louder model. First dark grey model weights 11kg. I plan to cut the weight 25% using LiPo battery. Here is the 3d plan for my 4th design.

I will build it using plywood which will be covered with 1mm black acryl. I searched for speaker part for a month. I was after high efficiency drivers to get out as many db per watt as possible. I found a DIY kit of a PA speaker which converts one watt of amplifier power to 94db of sound. This PA kit has horn tweeter so I had to alter the 3d plan a bit. Here's the final plan with horn tweeter in place:

When building portable audio devices it's important to choose amplifier with high efficiency. Class-d amps are good choice, I found my model over ebay. It gives 2x100w into 4ohm load when fed with 36V voltage. My battery has 18,5V voltage so I will get "only" 2x40W power from the amp.

Even more importand aspect is the sensitivity of the speakers connected to the amp. Sensivity tells how much sound speakers produces with 1 watt power. I chose Visaton diy kit which has 2x 8" bass drivers and a horn tweeter. These speakers will produce 94db of sound with 1 watt power. (pretty loud) I calculated with 40W power I will get about 120db of sound!

My design philosophy is to keep the electronics as simple as possible. The K.I.T.T scanner is great exception here Atleast on my scale. Led scanner has no other function that to look cool! It's more like a pseudo cool addition.

The center hole is reserved for the horn tweeter. Here's a pic of the drivers while I tested the crossover:

And here's a bonus photo of me in my fancy working environment. Modders spring fashion 2010:

First of all plywood is cheap and really easy to work with. Also thin plywood is pretty light. I think my whole box weights 3kg since I routed unnecessary areas thinner. Sound _quality_ isn't first priority in ghettoblaster so glassfiber would be fine but harder to work with. Glassfiber box with some plywood braces inside would be pretty optimal in my opinion. Weight and sound pressure come before sound quality for me with blasters Wall thickness in this box vary from 6mm to 12mm. My first model was thicker and it turned out to be unnecessary. As I've already tested this box it doesn't rattle or do anything unwanted